Hey guys,

What causes the rattle when going up a hill in a high gear then having to down shift to increase revs? Is it fixable?

Cheers!

Loose exhaust shields.
If its a manual and you let the revs drop too low under load, detonation. Try higher octane fuel, or shift down earlier.
Loose splitter in "Y" section. (If the 380 has one. lol)

Amongst other causes.

Hey Mad Max, thanks for your reply. It's an auto.

I get a really loud rattle when I start my car some days. Does it for about 30 seconds then goes away. Persists through acceleration too. Anyone have any ideas what it could be? It never happens while driving only on start up.

Cars Auto and Stock ES

I had something similar. Turned out to be a stone/stones from my gravel driveway lodged in exhaust shield.